Rated 4 out of 5 stars

When both addons are installed, many items in the Firefox's right-menu will disappear.

This review is for a previous version of the add-on (5.2). 

I am not going to install IDM CC, because it is loaded with dll's and accesses the Windows registry in order to determine which menu items should be visible. I just checked that there are no conflicting ID's. My guess is that the developers of IDM CC made an assumption about the menu structure which no longer holds when Column Reader is installed. My knowledge of XUL overlays is insufficient to be able to suggest a fix by merely reading the code. Perhaps the issue is gone after restarting Firefox (different installation order)?